Since the global positioning system (GPS) was introduced by the US military, new navigation satellite projects (e.g. by Russia (GLONASS), EU (Galileo)) have been lunched in order to give an alternative, improve or complement the existing GPS. Suppliers of navigation equipment see the value of trying to make use of all of the systems to get better navigation information and/or better coverage in built up areas where there are lots of blockages. One of these new navigation satellite projects is Chinas BeiDou Navigation Satellite System (BDS). BDS uses the same form of ephemeris as GPS for their IGSO (inclined geosynchronous orbit) and MEO (medium earth orbit) satellites. Unlike GPS, BDS also makes use of geostationary satellites and had to introduce a new form of ephemeris to support them. BDS introduces a new form for providing ephemeris data for geostationary satellites, wherein the ephemeris data is provided in relation to a reference plane that is tilted in reference to the equatorial plane. This is because for the geostationary orbits, which are over the equator, the orbit inclination would be near zero (or even zero) in classic GPS ephemeris form which can results in a singularity in the Keplerian orbit math. Determination of position and velocity of geostationary satellites is important for determining accurate navigation information (e.g. user position and/or user velocity), since an orbit of a geostationary satellite is influenced by a couple of factors. E.g. most geostationary orbits are instable (unstable) due to inhomogeneities in the earths form and due to influences of sun and moon, which causes a longitudinal drift of the satellite (especially if the orbit is not exactly geostationary) and therefore may need correction (from time to time). Further it is challenging to position a satellite in an exact geostationary orbit, which causes the satellite to move (wobble) in a small ellipse or FIG. 8 (in relation to a fixed point on earth). Therefore position and velocity of satellites positioned in geostationary orbits vary (slightly) which needs to be considered when calculating navigation information.